Carburetor



Jan. 18, 1944. H.'A. CARLs N ET AL CARBURETOR Original Filed (kit. 28, 1938 4 Sheets-Sheet 1 oKi S Q RLL Y O U I E T HM N N R R w A m W m DZ N Q ...A

Jan. 18, 1944. AycARLsou ETAL 2,339,320

CARBURETOR Original Filed Oct. 28, 1938 4 Sheets-Sheet 3' INVENTOR ARO D A. CARLSON ALEX NQSZWARGULSKI' I ATTORNEY -1 ,1944. m. ARLSQN p 2339.32

CARBURETOR Original Filed Oct. 28, 1938. 4 Sheets-Sheet 4 Fl G .13.

75 HJILII INVENTOR HAROLD A CARLSON ALEX N.-SZL\;VARGU LSK| a Q u l ATTORNEY Patented Jan. 18, 1944 CARBURETOR Harold A. Carlson. University" City, and Alex N.- Szwargulski, St. Louis, Mo., assignors to Carter- Carburetor Corporation, St. Lou'is,-Mo., a cornotation of Delaware Originalapplicatiori October 28, 1938,'Serial No. 237,454. Divided and this application June 10, 1941, Serial No; 397,358

1 Claim.

This invention relates to carburetors for internal combustion engines and consists particularly in novel meansfor controllingthe discharge from the idling passages. 1

This application is a division of our co-pending application, Serial No. 237,454, filed October 28, 1938, now Patent No. 2,261,794.

Automotive carburetors now in use are provided with idling systems interconnected with the'main fuel system in a manner to produce a gradual blending of the discharges from the two systems as the throttle-valve is opened. This arrangement has disadvantages, however, in that the suction applied through the idling passages tends to hold back the discharge from the main nozzle, so that greater depression must-be produced' at the mouth of the nozzle thanwould otherwise be necessary to draw fuel therefrom. In order to cause the main fuel nozzle to discharge at lower suctions, independent main and idling supply systems have been suggested, but these require some means for cutting out or substantially decreasing the idling discharge when the main nozzle starts to function, as without such means, the carburetor will flow excessively rich during the part throttlerange with both the main and idling systems discharging.

It is an object of the present invention to provide novel mean for restrictingthe idling discharge when the throttle valve is opened far enough, during normal operation, to insure-a discharge from the main nozzle.

Another object is to provide for a discharge of maximum richness from the idling port during the cranking and warm up periods when the choke valve is closed or only partially opened.

A more detailed object is to provide a throttle controlled device for closing off the connection between the idling system and the main fuel reservoir when the throttle valve has-been'opened to a predetermined extent.

Another detailed object is to provide an idling system having air vent means with valves controlled by the choke and throttle valves in a manner to render the idling system more efiective for discharging fuel when either or both valves are closed than when the valves are at least partially opened.

These objects and other more detailed objects hereafter appearing are attained substantially by the devices illustrated in the accompanyingdraw. ings. in which 7 Fig. 1 is aside view and longitudinal section showing a carburetor embodying one form oithe invention andis taken substantially on line l--[ of Fig; 4.

Fig. 2 is an enlarged partial section'taken on line 2-2 of Fig. 4.

Fig. 3 is an enlarged perspective view showing a detail of the metering pin operating structure in Figs. 1 and 4. i

Fig. 4 is a section through the float bowl and fuel metering mechanism of Fig.1 and'is'taken at 90 thereto, certain parts 'being'mov'ed into the section'plane for clearer illustration.

Fig. 5 is a view similar to Fig. 4'butishowing the main fuel metering valve open. i

Fig. 6 is an enlarged detail View of a; part-of the structure in Figs. 1 and 4 showing the main metering pin connection to theaccelerating pump lever. I c

Fig. '1 is a view corresponding to Fig. 41 but showing a second form of the invention.

Fig. 8 is a side viewshown partially in section on line 8--8 of Fig. 7 parts being omitted.

Fig; 9 is a side view and section corresponding to Figs. 4 and 7, but showing a third form of the invention.

Fig-l0 is an enlarged. view showinga detail of the structure in Fig. 9, the air valve and operating arm. beingshown in different positions.

Fig. 11 is a side view and section showing a carburetor embodying .a fourth formof the invention.

Figs. 12 and 13 are enlarged detail .views showing a portion of the structure in Fig. 11, .the throttle operated air valve being shown in difie'rent positions. r

,Figxl4 is an enlarged view showing the valve iorming'end of the throttle shaft inFigI'S;

In the accompanying drawings, like numerals indicate like parts in the various forms. The carburetor in Figs. 1-6, inclusive, has a downdraft mixture conduit including an air inlet horn I, ven'turi's 2 and an outlet portion 3 flanged as at 4 for attachment to the intake manifold (not shown) 'of an associated internal combustion engine. An unbalanced choke valve. 5 is mounted on shaft 6 in mean inlet horn and athrottle valve "-1 is mounted on s'hait t in the outlet-portion' The choke valve is automatically--controlled by thermostatic mechanism in housing A er may be manually controlled. Adjacentthemixture conduit is a bowl 9' within which fuel is maintained at a substantially constant level by the usual needle valveand' iio'at mechanism (not shown). Fuel is supplied to the-mixture-conduit through a main nozzle l-(l and idlingsystem' includmg passagesl i, i2 and-43 discharging through a port l4 adjacent and posterior to the edge of the throttle valve when closed. Idling passage I2 is provided with an air bleed port l2a I opening into the mixture conduit.

Main nozzle l communicates with the fuel bowl through a calibrated metering orifice elemeat I 5 which is variably restricted by a stepped metering rod l6 carried at its upper end by rocker lever l'l pivotally mounted on post I9 projecting above the bowl cover. Lever H at one end is connected to the throttle valveby means of a link [9 and crank 20 rigid withthe throttle shaft and at the other end is connected by means of a link 2| to fuel pump piston rod 22. Rod l6 has an enlargement 23 near its lower extremity arranged to seat on and close meteringelement when the throttle valve is closed. "A spring 24, interposed between arm I! and rod [6 (Fig. 6), provides for yielding connection of lever I? and metering rod [6.

The idling system communicates with the fuel bowl through an orifice '26 which connects with idling passage II by means of a cross passage 21. A calibrated metering tube 28 is mounted in passage H. Associated with port 26 is a valve 29normally urged upwardly towards its closed position by a coiled spring 30 seated upon a threaded plug 3|. A rod 32 projects upwardly from'valve 29 through port 26 and through the top of the fuel bowl and has a cross piece 33 at its upper extremity. A lug 34 projects from pump rocker lever I! in position to engage cross piece 33 when the throttle valve issubstantially closed to force rod 32 downwardly and open valve 29.

Pivotally supported at 36, on the outer wall of the carburetor air horn portion is a bell crank lever 31 (see Fig. 3) having laterally projecting lugs 38 and 39 at its extremities. Choke shaft 6 projects slightly beyond the wall of the air horn and, at its extremity is provided with a lateral pin or finger 49 disposed to engage lug 38 on crank 31 when the choke valve is closed to urge crank 31 counter-clockwise (Fig. 5). Lug 39 is in position to engage cross piece 33, when crank 31 is so moved, to force rod. 32 downwardly and open valve 29. Thus, valve 29' is controlled by both the choke and throttle valves so as to insure opening of theeffective fuel metering orifice in the idling system to the fuel bowl when either the choke or throttle is closed. The throttle control is arranged to permit closing of valve 29 under the influence of spring 39 when the throttle valve is opened sufiiciently to cause a discharge from the main fuel nozzle under normal operating conditions, thuscutting on. fuel supplied to the idling system and, in effect, increasing to infinity the ratio of air to fuel in the discharge from the idling system. The choke valvecontrol may be arranged to hold the valve open only when the choke valve is fully closed, in order to and, at its upper extremity, communicates with the interior of the air horn above the choke valve as at 41. Choke shaft 611 extends into passage 46 and is slotted to form a valve structure 48.

, Passages 46 and 41 constitute an air vent for the idling system which is controlled by Valve structure 48. This vent is, preferably, of sufficient capacity relative to the smallest section of idling passages 45, ll, l2 and I3 and port l4 to effectively prevent the drawing of idling fuel through orifice 43 and restriction 49, when the provide a rich starting mixture, or valve 29 may 7 be held open during any desired portion of the choke opening movement.

In Figs. 7 and 8, rod 32a and valve 29a are provided with a longitudinal passage as at 42 to provide a constant feed to the idling system regardless of the position of valve 29a. In this form, valve 29a is controlled from the pump rocker arm as in the previous form. An additional fuel feed to the idling system is provided at 32, this orifice communicating with idling passage II by means of passages 44 and 45, the former being formed on theinner wall of the fuel bowl. .A vertical passage. 46 forms a continuation of passage 44 choke valve is opened, aligning slot 48 with passage 46. The idling system is thereafter fed through orifice 26 until the throttle valve is opened sufficiently to permit closing of valve 29a. When valve 29a is closed, a restricted fuel discharge through the idling system may be obtained by means of by-pass 42, where such discharge is required to obtain the proper mixture proportions, particularly during part throttle op.- eration. In this form, as in the first form, means is provided for substantially restricting the discharge through the idling system when the choke and throttle valves are at least partially opened, an idling fuel discharge of maximum richness being provided when both the choke and throttle valves are substantially closed. In starting a cold engine, the choke will be closed and the throttle partly open permitting the feeding of fuel through port 43 and the idling system.

In the third form in Figs. 9 and 10, the idling system communicates with the fuel bowl through a calibrated tube 59, passages 5|, 52 and 53 forming an air vent into the interior of the air horn. The end of choke shaft 62) extends into passage 52 and is slotted to form a valve structure 48a. A rocker lever Fla is pivotally supported above the fuel bowl and connected at one end to the throttle valve, as in Figs. 4 and 7, by means of link' l9 and arm 29, and has holes 55 at its opposite end for connection to the fuel pump piston rod (not shown). The intermediate portion 'of' rocker lever 54 is shaped to form a cam as at 56. Interposed in passage 5i is a valve 51 normally urged upwardly towards its closed position by a coiled spring 58 seated on plug 59. A stem 69 projectsupwardly from valve 51 and is in position to be engaged by cam 56 when the throttle valve is opened sufficiently to insure a discharge from the main nozzle under normal operating conditions, to open valve 51. When the throttle valve is substantially closed, cam 56 permits closing of valve 51 by spring 58 to out off the air bleed. Preferably the vent is of sufficient 'capacity'to effectually prevent discharge through the idling system when both the choke and throttle valve are at least partially opened, although, if desired, a limited discharge through the idling system may be maintained where this .is necessary'to obtain a desired part throttle mixture quality curve. 7

In the fourth form in Figs. 11-14, which is very similar-to the-third form, the idling system is 'formed by passages 65, 66 and 6'! communicating with the fuel bowl through orifice B8 and discharging adjacent the edge of the throttle valve, when closed,.by means of port 69. Passages 19. H, 12 and 73 form an air vent for the idling systemr'communicating with the atmosphere as at '14;' .,Choke shaft 6?) extends into passage .H and .is slotted to form valve structure 48a, as in the previous form. The endof the throttle shaft extends into passage 13 and is cut out to form ,valve structure 15. The slot in valve structure 48a is arranged to align with passage H when the choke valve is open. Solid portions 16 in valve structure 75 register with passage 13 when the throttle valve is substantially closed, and, when the throttle valve is opened far enough to permit discharge from the main nozzle under normal operating conditions, these solid portions are in position so as to Open the vent. Thus, when both the choke and throttle Valves are at least partially open, the air vent will be open so as to substantially increase the ratio of air to fuel in the idling discharge. Figs. 12 and 13 show the throttle valve structure 15 in various positions relative to passage 13.

The arrangement of the carburetor in general as well as the various fuel supply passages is not essential and these may be modified as desired. The invention is particularly adaptable to carburetors having independent idling systems, but features thereof may be utilized to advantage in carburetors having the interconnected idle and main fuel systems in the latter case, it being important that the fuel valve control and effective metering restriction in the idling system, since, ordinarily, the main metering elements which control the main nozzle discharge are ineffective as control means for the idling mixture.

The exclusive use of all such modifications as come within the scope of the appended claims is contemplated.

We claim:

In a carburetor, a mixture conduit, a fuel reservoir, a throttle and a choke in said conduit, main fuel supply means discharging into said conduit anterior to said throttle, an idling passage communicating with said reservoir independently of said main supply means and discharging into said conduit on both sides of said throttle when closed, said idling passage having an effective air bleed port, a valve controlling said port, and mechanism for operating said valve including an operative connection between the same and said choke for closing said valve to stop the flow of air into said idling passage when said choke is closed for starting and for opening said valve to increase the air in said passage when the choke is substantially open for normal low speed running.

' HAROLD A. CARLSON.

ALEX N. SZWARGULSKI. 

